Preheat the oven to 350°F.

Brush a 9x13 inch baking dish with melted butter.

Take one sheet of phyllo dough and place it in the baking dish. Brush it with melted butter. Repeat with 7 more sheets of phyllo dough.

Sprinkle 1/2 cup of ground walnuts over the phyllo dough.

Layer another 8 sheets of phyllo dough, brushing each sheet with melted butter.

Sprinkle another 1/2 cup of ground walnuts over the phyllo dough.

Repeat steps 3-6 until all the ground walnuts are used up.

Layer the remaining sheets of phyllo dough on top, brushing each sheet with melted butter.

Use a sharp knife to cut the baklava into diamonds or squares.

Bake the baklava for 30-40 minutes, or until golden brown.

In a small saucepan, combine sugar, water, honey, lemon slices, and cinnamon stick.

Bring the mixture to a boil, stirring occasionally.

Reduce the heat and simmer for 10-15 minutes, until the syrup thickens slightly.

Remove the lemon slices and cinnamon stick.

Once the baklava is cooked, remove it from the oven.

Pour the hot syrup over the baklava.

Let it cool for at least 2 hours before serving.